using of Drawing instruments

1. Introduction to
TECHNICAL DRAWING

2. Definition of Technical Drawing
• Technical Drawing is used to convey
information of a technical nature.
• Technical Drawing is prepared with the use of
mathematical drawing instruments. For this
reason they are often called mechanical
drawing.

3. Method used to produce Technical
Drawings
• Traditional Method
Sketching
 Computer-
Aided drafting
(CAD)

4. Traditional Methods Drawing Instrument
• Tee- Square ( T-square)
• Set- Squares
• Compass
• Pencils
• Dust free Eraser
• Radius & Circle Template
• flex or French curve
• Erasing shield

5. Tee-Square
•A T-square is used by draftsmen
primarily as a guide for drawing
horizontal lines.
• It also guide a set square to draw
vertical or diagonal lines

6. Set - Squares
• Set squares are used in conjunction with T-squares to
draw horizontal lines and accurate angles.
• There are two main types of set square:
45 degree 30/60 degree

7. Compass
• A compass is an instrument used to draw circles
or the parts of circles
Spring Bow Compass
Beam or Compass
Drop Compass
Proportional Compass

8. Compass point

9. Dust- free Eraser

10. Pencils
• A pencil is graded according to the hardness
of its lead from 7H(very hard to 7B very soft)
Draughting Note Art Work
4H 3H 2H H HB B 2B 3B 4B

11. Pencil points
• All pencil lines should be thin and clear. To obtain
these the pencil must be kept sharp.

12. Radius & circle Template
to save time, many draftsmen now use
templates for drawing small circles and
arcs.

13. Flex Curve& French Curve
• It is used in manual drafting to draw smooth
curves of varying radii.
French Curve
Flex Curve

14. Erasing shield
• These thin pieces of metal have a variety of
openings to permit the erasure of fine detail
line or note work disturbing nearby work that
is to be left on the drawing.

15. Brushes
• A light brush is used to keeping the drawing area
clean. By using a brush to remove eraser particles
and any accumulated dirt, the draftsmen avoids
smudging the drawing

16. Application of technical drawings
• Building drawing
Schematic drawing
Mechanical drawing